Negative-resistance device



June 30, 1925.

A. W. HULL NEGATIVE RESISTANCE DEVICE Filed July 5. 1919 Inventor" Albert W. Hull,

fi q M,

His Attorney Patented June 30, 1925'.

ALBERT W. HULL, OF SOHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC 1 1,544,321" UNITED STATES PATENT OFFICE.

COMPANY, A CORPORATION OF NEW YORK.

NEGATIVE-RESISTANCE DEVICE.

- Application filed July 5,

. To all whom it may concern:

Be it known that I, ALBERT W. HULIJ, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new andv useful Improvements in Negative-Resistance Devices, of which the following is a specification.

My present invention relates to devices having negative resistance characteristics and more particularly to devices of this type which are adapted to be operated by means of electron currents flowing across an evacuated space.

One of the objects of my invention is to provide a negative resistance device which will be simple in construction and Will be adapted to the various purposes to which such a device may be applied. A further and more specific object of my device is to provide an efficient form of amplifier for feeble electric currents.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, the invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figs. 1 and 3 show in perspective two forms of my device, and Figs. 2 and 4 illustrate two other modifications partly in section and partly in pers ective.

In all forms of my device illustrated an evacuated receptacle 1 is provided 'in which are sealed two electrodes 3 and 4, the electrode 4 being of filamentary form so that current may be passed through it for heating it to incandescence to cause it to emit electrons. In the form of my invention shown in Fig. 1, one of the leading-in conductors for electrode 4 has an extension of electrode 4 and which is interposed between electrodes 3 and 4 and formsa third electrode 8. The direct current source ,5, which is connected to the leading-in conduc-- tors 6 and 7 fpr passing current through electrode 4, has its positive terminal connected to leading-in conductor 7 so that electrode 8 Will be at a positive potential with respect to electrode 4. Electrode has impressed thereon by means of the direct 1919. Serial No. 308,852.

current source 9 a potential which is positive with. respect to that of leading-in conductor 6, but which is somewhat smaller the external circuit between electrodes 3 and 4, it will be found that the current in that circuit will vary over'a certain operating range inversely as the potential applied to the circuit.

I have indicated in Fig. 1 one manner in which the device may be utilized as anamplifier. The current which is to be amplified is supplied to the circuit between electrodes 3 and 4 by means of a transformer 10. In cluded in this circuit is also a resistance 11 having positive resistance characteristics. If this resistance has a value of the same order of magnitude as the resistance of the evacuated space between the electrode 3 and the electrode 4, it will be found that potential variations will be set up across the terminals of resistance 11 of much greater mag nitude than those applied to the circuit by transformer 10. These-potential variations may be supplied by means of conductors 12 to any suitable device. for obtaining an indication of the currents which are being amplified.

. The device shown in Fig. 2 is similar to that shown in Fig. 1 with the exception that in this case the electrode 8 is made in the form of a s iral surrounding the heated portion 4. T e electrode 3 is also ,made in the form of a cylinder surrounding the spiral electrode 8.

The operation of the devices of Figs. 1

and 2 whereby the result described is obtained, is substantially as follows:

Electrons emitted by the electrode 4 are attracted by the positive field set up by the electrode 8 and thereby given a high ve locity. If the potential of electrode 3 is negative with respect to that of electrode 4 all of these electrons will either reach electrode 8 or return to electrode 4. If, however, the electrode 3 is positive with respect to electrode 4 some of the electrons emitted by electrode 4 will reach electrode 3 by reason of the high velocity'given them by the positive field of electrode 8 and the attraction .of the positive field produced by electrode 3. As the positive potential of electrode 3'is increased more and more electrons will reach electrode 3 and the velocity with which the p also increase. hen the potential is increased sufiiciently these electrons will reach electrode 3 with such velocity that they will be able by their impact to liberate secondary electrons which are attracted to the more positive electrode 8. As the positive potential applied to the electrode 3 increases a point will be reached at which the number of secondary electrons emitted increases faster than the increase in the number of primary electronsreaching electrode 3. The

current in the external circuit between electrodes 3 and 4 will then begin to decrease. As the positivepotential of electrode 3 is further increased a point may finally be reached at which each primary electron reaching electrode 3 will on the average liberate one secondary electron which returns to electrode 8. v Current in the external circuit will then be zero. A further increase in the positive potential of electrode 3 will cause the liberation of a greater number of secondary electrons than the number of primary electrons received thereby. As a result the current in the external circuit will reverse in direction. This will continue until the positive potential of the electrode 3 approaches that of the electrode 8. The current in the external circuit will then begin to approach the zero point and increase rapidly in the original direction. There will be a definite range of applied potentials to electrode 3 over which the current in the external circuit varies inversely as the potential applied to that circuit, and the device when operated over this range is particularl adapted for use as an amplifier as well as or various other purposes, as set forth in my U. S. Patents 1,313,187 and 1,313,188, of Au st 12, 1919.

In t e devices shown in Figs. 3 and 4, the electrodes are arranged somewhat differently and the result is consequently brought about in a somewhat different way. Inthese cases the electrode 3 is interposed between ion the electrode 4 and the electrode 8. The electrode 3 has impressed thereon by means of the battery 9, a potential which is preferably somewhat negative with respect to that of the electrode 4. In this case there will be a-flow'of electrons from electrode 4 to electrode 8. Since the electrode 3 is negative with respect to electrode 4 no electrgns will be received by electrode 3. If, however, the tube contains a small amount of s the electrons passing from 4 to 8 will lonize' this gas and the positive [ions thus produced will be attracted'by the negative electrode 3 and produce a current inthe external circuit between electrode 3 and elec-. trode 4. The negative potentialof electrode 3, however, restrains the free passage of electrons between the electrodes 4 and 8,

strike this electrode will I and hence limits the number of electrons passing through the space and the number of positive ions produced. As the negative potentialof the electrode 3 is decreased .the' flow of electronsbetween 4 and 8 increases,

the number of positive ions produced is increased, and hence the current flowing in the external circuit between electrodes 3 and 4 will increase, that is, the current in this circuit will vary inversely as the potential applied to the circuit. This action willcontinue until the potential of electrode 3 becomes substantially equal to or positive with respect to that of electrode 4. The electrode 3 will then be able to receive negative electrons and the current in the circuit between electrodes 3 and 4 will become zero and reverse in direction because of the fact that it becomes a current carried by negative electrons instead of positive ions.. This device, as indicated in Fig. 3, may also 'be used for purposes of amplification in the samemanner asthe device shown in Fig. 1.

The device shown in Fig. 4 ,difl'ers from that shown in Fig. 3 only-in the fact that the electrode '8 is made n the form of a cylinder surrounding electrode 3.

While I have indicated the preferred embodiments of my invention of which I am now aware-and have also indicated only one specific application for which my invention may be employed, it, will be apparent that my invention is by no means limited to the exact forms illustra d or the use indicated, but that many vari tions may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

lVhat I claim as new and desire to secure by Letters Patent of the United States, 1s,

1. ing an evacuated receptacle containing an electron emitting electrode and two cooperating electrodes to one of which one end of the electron emitting electrode is directly connected electrically within the receptacle.

2. An electron discharge device comprising an evacuated receptacle containing an electron emitting electrode and. two cooperating electrodes, one of saidcooperating electrodes constituting a portion of the connections by which current is supplied to the electron emitting electrode.

3. ,Anelectron dischargev device comprising an evacuated receptacle containing an electron emitting electrode and two cooperating electrodes, one ofsaid electrodes serving as a" mechanical support for one end of the electron emitting electrode and constituting a portion of the connections by which current is supplied to the electron emitting electrode. 1

4. An electron discharge device compris- An electron discharge device comprising an evacuated receptacle containing three electrodes, means for supplying current to one of said electrodes for heating it to incan- V descence, one of the other electrodes being so arranged that heating current for the first electrode may be supplied therethrough, and means for producing a current between the heated electrode and the third electrode which varies inversely as the potential between said electrodes.

6. An electron discharge device comprising an evacuated receptacle containing a filamentary electrode and two other cooperating electrodes, one end of said filamentary electrode being connected to one of said other electrodes within the receptacle, and means for passing current through said filamentary electrode and the other electrode to which it is connected to heat said filamentary electrode to incandescence.

7. An electron discharge device comprising an evacuated receptacle containing a filamentary electrode and two other cooperating electrodes, one end of said filamentary electrode being connected to one of said other electrodes within the receptacle, means for passing current through said filamentary electrode and the other electrode to which it is connected to heat said filamentary electrode to incandescence, and means for producing a current between said filamentary electrode and the third electrode which varies inversely as the potential between said electrodes.

8. An electron discharge device comprising an evacuated receptacle containing a filamentary cathode and two other cooperating electrodes, one end of said filamentary electrode being connected to and mechanically supported by one of said other electrodes, and means for passin current through said filamentary electro e and the other electrode to which it is connected to heat said filamentary electrode to incandescence.

' 9. An electron discharge device comprising an evacuated receptacle containing a filamentary cathode and two other cooperating electrodes, one end of said filamentary electrode being connected to and mechanically s 1 1pported by one of said other electrodes,

means for passing current through said filamentary electrode and the other electrode to which it is connected to heat said filamentary electrode to incandescence, and means for producing a current between said filamentary electrode and the third electrode which varies inversely as the potential between said electrodes.

10. A thermionic amplifier comprising an evacuated vessel containing a filamentary electrode and two other cooperating electrodes, one end of said filamentary electrode being connected to one of the other elec trodes within the receptacle, means for passing current through said filamentary electrode and the other electrode to which it is connected to heat said filamentary electrode to incandescence, an electrical circuit between said filamentary electrode and the third electrode, means for producing in said circuit a current which varies inversely as the potential. between said electrodes, means for applying potentials to be amplified to said circuit, and means for deriving from said circuit amplified potential variations corresponding to those applied to the circuit.

11. An electron discharge device comprising an evacuated receptacle containing an electron emitting electrode and two coopcrating electrodes, one of said cooperating electrodes being interposed between the other two and constituting a portion of the con-' nections by which current is supplied to the electron emitting electrode.

12. An electron discharge device comprising an evacuated receptacle containing three electrodes, means for supplying current to one of said electrodes for heating it to incandescence, one of the other electrodes being so arranged that heating current for the first electrode may be supplied therethrough and means dependent upon gas ionization in the device for producing a current between the heated electrode and the third electrode which varies inversely as the potential between said electrodes.

14. An electron discharge device compris ingan evacuated receptacle containing three electrodes, a source of direct current for heating one of said electrodes to incandes cence to cause it to emit electrons, one of the other electrodes being connected to the positive end of the electron emitting-electrode within the receptacle so as to have pro- .duced thereon a ,positive electrostatic field sources being so chosen and the device being so constructed that a current will flow from the electron emitting. electrode to the third g mg an evacuated receptacle, an electron emitelectrode which will vary inversely potential between said. electrodes.

15. Ari-electron discharge device comprising an evacuated receptacle, an electron emitting electrode and two cooperating as the electrodes, leading-in conductors for supply.-

ing current to said electrodes, one of said cooperating electrodes being of spiral form interposed between the other two and having one point therein connected to a leading-in conductor and another. point connected to the electron emitting electrode whereby it constitutes a portion of th connectionsby which current is supplied to the electron emitting electrode.

16. An electron discharge device comprising an evacuated receptacle containing an electron emitting electrode, and two acooperating electrodes to one of which one end of the electron emitting electrode is directly connected electrically within the receptacle and one of said cooperating electrodes being in the form of a spiral conductor interposed between the other two electrodes. 17. An electron discharge device comprising. .an. evacuated receptacle, an electron emitting electrode'and two cooperating electrodes and leading-in conductors for supplying current to said electrodes, one of said cooperating electrodes being of spiral form having one point therein connected to a leading-in conductor and another point connected to said electronemitting electrode whereby it forms a portion of the connections by which current is supplied to the electron emitting electrode.

18. An electron discharge. device compristing electrode and two cooperating electrodes, and leading-in conductors for supplying current to said electrodes, one of said electrodes having one point connected to a leadin -in conductor and another point connecte to one end of the electron emitting electrode, the opposite end of the electron emitting electrode being connected to a second lead ing-in conductor.

19. An electron discharge device comprising an evacuated receptacle, an electron emitting electrode and two coo crating electrodes, leading-in conductors or supplying current to said electrodes, one of said electrodes being of spiral form interposed between the other two and having one point connected to a leadin -in conductor and another point connecte toone end of the electron emitting electrode, the opposite end of the electron emitting electrode being connected to another leading-in conductor.

20. An electron discharge device comprising an electron emitting electrode, an electrode of'spiral form surrounding said electron emitting electrode, and a third electrode surrounding said spiral electrode, said spiral electrode constituting a portion of the connections by whichcurrent is supplied to the electron emitting electrode.

In witness whereof, I have hereunto set my hand this 3rd day of July, 1919.

' ALBERT W. HULL. 

